Quaelibet propositio asserit seipsam esse veram
Quaelibet propositio asserit seipsam esse veram Every proposition asserts itself to be true. This idea can be found as early as Bonaventura:
- An affirmative proposition makes a double assertion: one in which the predicate is affirmed of the subject and the other in which the proposition is asserted to be true. By virtue of the first assertion an affirmative proposition is differentiated from a negative one, which denies the predicate of the subject. So far as the second assertion is concerned, however, affirmative and negative statements agree since they both assert something to be true. Contradiction is concerned not with the second type of assertion but with the first. For when it is stated that no truth exists, insofar as it negates the predicate of the subject this proposition does not imply its opposite, viz that some truth exists. But to the extent that it asserts this to be true, it does entail that some truth exists."[1]
Burley says ‘Quaelibet propositio asserit seipsam esse veram,’ De Puritate Artis Logicae Tractatus Longior, The Franciscan Institute, St Bonaventure, 1955, p. 25, see also On the Purity of the Art of Logic, transl P.V. Spade, Yale UP, New Haven and London 2000, p.108. ‘Quilibet dicens asserit suum dictum esse verum’. (Roure, M.-L. (1970). La problematique des propositions insolubles au XIIIe siecle et au debut du XIVe, suivie de l'edition des traites de W. Shyreswood, W. Burleigh et Th. Bradwardine. Archives d'Histoire Doctrinale et Litteraire du Moyen Age, 37:205-326, p. 272. See also Duns Scotus, Questions on the Perihermenias Lib. I Questiones 7-9 x10 (Andrews et al., 2004, I p. 181) ‘Quaelibet propositio significat se esse veram’.
Geulincx gives the following argument in support of this. Any proposition says something to be (the case), and says it to be what it says it to be. But something being as the proposition says it to be is for it to be true. So it says itself to be true.[2]
Signification and reality
A similar formula connects truth, reality and signification. Albert of Saxony in treatise 6 of his Perutilis Logica says that “a true proposition is one such that things are however it signifies they are” (not in Logic Museum).
Buridan in Tractatus de Consequentiis 1.1.3 says that according to some, every true proposition is true because however it signifies, so it is (in reality). Aliqui ponunt ex eo omnem propositionem veram esse veram quia qualitercumque ipsa significat ita est. See also his questions on the Posterior Analytics PA I.10 (Quaeritur utrum ad veritatem propositionis requiratur et sufficiat quod qualitercumque ipsa significat ita sit).
References
Truth, Signification and Paradox, Stephen Read, 2015.
Notes
- ↑ Quaestiones disputatae de mysterio Trinitatis, q1 a1, translated in Wippel and Wolter eds. Medieval Philosophy. The Free Press, New York. 1969, pp. 310-11.
- ↑ Sit enunciatio quaecunque, nempe A. Dico quod A dicat se esse veram. Quia A dicit esse, et dicit esse quod dicit esse, sed esse id, quod A esse dicit, est A esse veram. Cum igitur A prius dicat, dicit etiam posterius, seu A dicet A, id est seipsam, veram esse." (Logica fundamentis suis, a quibus hactenus collapsa fuerat, restituta. Henricus Verbiest, Leiden 1662, II.i.1.4), reprinted inLand, ed, Arnold Geulincx: Opera Philosophica. Martinus Nijhoff, The Hague. 3 volumes, 1891, vol. I pp. 165-454, p. 234) According to Read, similar proofs are found in Albert of Saxony and John Buridan. Read, S. (2002). The liar paradox from John Buridan back to Thomas Bradwardine. Vivarium, 40:189-218.
